<template>
  <div id="root">
    <hr class="three" />
    <H2>TodoListEvent 自定义事件进行 数据传递（子-->父）</H2>
    <div class="todo-container">
      <div class="todo-wrap">
        <MyHeader @addTodo="addTodo" /><!-- 添加一个自定义组件事件 用于 子组件==>父组件 通信-->
        <MyList :todos="todos" :checkTodo="checkTodo" :deleteTodo="deleteTodo" />
        <!--
             在父组件中：<Demo @事件名="test"/> 或 <Demo v-on:事件名="test"/>
             子组件：声明触发自定义事件：this.$emit('atguigu',数据)
              -->
        <MyFooter :todos="todos" @checkAllTodo="checkAllTodo" @clearAllTodo="clearAllTodo" />
      </div>
    </div>
  </div>
</template>

<script>
import MyHeader from './MyHeader'
import MyList from './MyList'
import MyFooter from './MyFooter.vue'

export default {
  name: 'TodoListEvent',
  components: {MyHeader, MyList, MyFooter},
  data() {
    return {
      //由于todos是MyHeader组件和MyFooter组件都在使用，所以放在App中（状态提升）
      todos: JSON.parse(localStorage.getItem('todos')) || []
    }
  },
  methods: {
    //添加一个todo
    addTodo(todoObj) {
      this.todos.unshift(todoObj)
    },
    //勾选or取消勾选一个todo
    checkTodo(id) {
      this.todos.forEach((todo) => {
        if (todo.id === id) todo.done = !todo.done
      })
    },
    //删除一个todo
    deleteTodo(id) {
      this.todos = this.todos.filter(todo => todo.id !== id)
    },
    //全选or取消全选
    checkAllTodo(done) {
      this.todos.forEach((todo) => {
        todo.done = done
      })
    },
    //清除所有已经完成的todo
    clearAllTodo() {
      this.todos = this.todos.filter((todo) => {
        return !todo.done
      })
    }
  },
  watch: {
    todos: {
      deep: true,
      handler(value) {
        localStorage.setItem('todos', JSON.stringify(value))
      }
    }
  },
}
</script>

<style>
/*base*/
body {
  background: #fff;
}

.btn {
  display: inline-block;
  padding: 4px 12px;
  margin-bottom: 0;
  font-size: 14px;
  line-height: 20px;
  text-align: center;
  vertical-align: middle;
  cursor: pointer;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2), 0 1px 2px rgba(0, 0, 0, 0.05);
  border-radius: 4px;
}

.btn-danger {
  color: #fff;
  background-color: #da4f49;
  border: 1px solid #bd362f;
}

.btn-danger:hover {
  color: #fff;
  background-color: #bd362f;
}

.btn:focus {
  outline: none;
}

.todo-container {
  width: 600px;
  margin: 0 auto;
}

.todo-container .todo-wrap {
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
}
</style>
